IViewAutomationPeer Interfaccia

Definizione

Spazio dei nomi:

System.Windows.Automation.Peers

Assembly:

PresentationFramework.dll

Consente a una visualizzazione personalizzata di un oggetto ListView derivante da ViewBase di implementare funzionalità del peer di automazione specifiche della visualizzazione stessa.

public interface class IViewAutomationPeer

public interface IViewAutomationPeer

type IViewAutomationPeer = interface

Public Interface IViewAutomationPeer

Derivato

System.Windows.Automation.Peers.GridViewAutomationPeer

Esempio

Il codice seguente mostra una visualizzazione personalizzata che implementa IViewAutomationPeer in una classe separata per gestire un pulsante visualizzato nella parte superiore del ListView controllo.

public class OneButtonHeaderView : ViewBase
{
    protected override IViewAutomationPeer GetAutomationPeer(ListView parent)
    {
        return new OneButtonHeaderViewAutomationPeer( this, parent );
    }

Public Class OneButtonHeaderView
    Inherits ViewBase
    Protected Overrides Function GetAutomationPeer(ByVal parent As ListView) As IViewAutomationPeer
        Return New OneButtonHeaderViewAutomationPeer(Me, parent)
    End Function

public class OneButtonHeaderViewAutomationPeer : IViewAutomationPeer
{
    ListView m_lv;

    public OneButtonHeaderViewAutomationPeer(OneButtonHeaderView control, ListView parent)
    {
        m_lv = parent;
    }

    ItemAutomationPeer IViewAutomationPeer.CreateItemAutomationPeer(Object item)
    {
        ListViewAutomationPeer lvAP = UIElementAutomationPeer.FromElement(m_lv) as ListViewAutomationPeer;
        return new ListBoxItemAutomationPeer(item, lvAP);
    }

    AutomationControlType IViewAutomationPeer.GetAutomationControlType()
    {
        return AutomationControlType.List;
    }

    List<AutomationPeer> IViewAutomationPeer.GetChildren(List<AutomationPeer> children)
    {
        // the children parameter is a list of automation peers for all the known items
        // our view must add its banner button peer to this list.

        Button b = (Button)m_lv.Template.FindName("BannerButton", m_lv);
        AutomationPeer peer = UIElementAutomationPeer.CreatePeerForElement(b);

        //If children is null, we still need to create an empty list to insert the button
        children ??= new List<AutomationPeer>();

        children.Insert(0, peer);

        return children;
    }

    Object IViewAutomationPeer.GetPattern(PatternInterface patternInterface)
    {
        // we can invoke the banner button 
        if (patternInterface == PatternInterface.Invoke)
        {
            Button b = (Button)m_lv.Template.FindName("BannerButton", m_lv);
            AutomationPeer peer = UIElementAutomationPeer.FromElement(b);
            if (peer != null)
                return peer;
        }

        // if this view does not have special handling for the pattern interface, return null
        // the ListViewAutomationPeer.GetPattern default handling will be used.
        return null;
    }

    void IViewAutomationPeer.ItemsChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs e) { }

    void IViewAutomationPeer.ViewDetached() { }
}

Public Class OneButtonHeaderViewAutomationPeer
    Implements IViewAutomationPeer
    Private m_lv As ListView

    Public Sub New(ByVal control As OneButtonHeaderView, ByVal parent As ListView)
        m_lv = parent
    End Sub

    Private Function CreateItemAutomationPeer(ByVal item As Object) As ItemAutomationPeer Implements IViewAutomationPeer.CreateItemAutomationPeer
        Dim lvAP As ListViewAutomationPeer = TryCast(UIElementAutomationPeer.FromElement(m_lv), ListViewAutomationPeer)
        Return New ListBoxItemAutomationPeer(item, lvAP)
    End Function

    Private Function GetAutomationControlType() As AutomationControlType Implements IViewAutomationPeer.GetAutomationControlType
        Return AutomationControlType.List
    End Function

    Private Function GetChildren(ByVal children As List(Of AutomationPeer)) As List(Of AutomationPeer) Implements IViewAutomationPeer.GetChildren
        ' the children parameter is a list of automation peers for all the known items
        ' our view must add its banner button peer to this list.

        Dim b As Button = CType(m_lv.Template.FindName("BannerButton", m_lv), Button)
        Dim peer As AutomationPeer = UIElementAutomationPeer.CreatePeerForElement(b)

        'If children is null, we still need to create an empty list to insert the button
        If children Is Nothing Then
            children = New List(Of AutomationPeer)()
        End If

        children.Insert(0, peer)

        Return children
    End Function

    Private Function GetPattern(ByVal patternInterface As PatternInterface) As Object Implements IViewAutomationPeer.GetPattern
        ' we can invoke the banner button 
        If patternInterface = PatternInterface.Invoke Then
            Dim b As Button = CType(m_lv.Template.FindName("BannerButton", m_lv), Button)
            Dim peer As AutomationPeer = UIElementAutomationPeer.FromElement(b)
            If peer IsNot Nothing Then
                Return peer
            End If
        End If

        ' if this view does not have special handling for the pattern interface, return null
        ' the ListViewAutomationPeer.GetPattern default handling will be used.
        Return Nothing
    End Function

    Private Sub ItemsChanged(ByVal e As System.Collections.Specialized.NotifyCollectionChangedEventArgs) Implements IViewAutomationPeer.ItemsChanged
    End Sub

    Private Sub ViewDetached() Implements IViewAutomationPeer.ViewDetached
    End Sub
End Class

Metodi

CreateItemAutomationPeer(Object)	Crea una nuova istanza della classe ItemAutomationPeer.
GetAutomationControlType()	Ottiene il tipo di controllo per l’elemento associato a IViewAutomationPeer.
GetChildren(List<AutomationPeer>)	Ottiene la raccolta di elementi figlio immediati dell'Automazione interfaccia utente peer specificato.
GetPattern(PatternInterface)	Ottiene il pattern di controllo associato all'oggetto patternInterface specificato.
ItemsChanged(NotifyCollectionChangedEventArgs)	Chiamato da ListView quando l’insieme di elementi viene modificato.
ViewDetached()	Chiamato quando la visualizzazione personalizzata non è più applicata al ListView.

Vedi anche

• ViewBase
• GetAutomationPeer(ListView)